A conventional measuring tube is known from EP 0 458 998 B1 for use in a motor vehicle. The flow straightener consists of a honeycomb grid made from plastic, with a metal grid welded to its edge. The flow straightener is fastened to the measuring tube inlet, for example, by means of hot caulking.
In the known flow straightener, vibrations occurring in the vehicle may result in a mechanical failure of the metal grid. Moreover, it is possible that, on account of ageing, the influence of temperature, moisture absorption and/or a change in the measuring tube geometry, the metal grid buckles in an undefined manner, which may lead to a swirling of the air flow.